SOLUTION: This problem has three questions with it, im sorry. You plan to invest some money in an account paying simple intrest. What intrest rate do you need if you invest $1500, and want

Question 891538: This problem has three questions with it, im sorry.
You plan to invest some money in an account paying simple intrest. What intrest rate do you need if you invest $1500, and want to end up with a total of $1800 after two years?
How much do you need to invest if the intrest rate is 5%, and you need a total of $1800 in 4 years?
How long do you need to wait to have a total of $2000 if you invest $1600 at 5% intrest?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
The simple interest formula: I = PRT, where:
I = interest earned
P = principal (initial amt)
R = Interest rate in decimal form
T = time in years
:
What intrest rate do you need if you invest $1500, and want to end up with a total of $1800 after two years?
Amt of interest (I) is 1800-1500 = 300, find R
300 = 1500*R*2
300 = 3000R
R = 300/3000
R = .10 which is 10%
:
How much do you need to invest if the intrest rate is 5%, and you need a total of $1800 in 4 years?
Find P
300 = P*.05*4
300 = .2P
P = 300/.2
P = $1500
:
How long do you need to wait to have a total of $2000 if you invest $1600 at 5%
intrest?
Interest earned here: 2000-1600 = 400
400 = 1600*.05*T
400 = 80T
T = 400/80
T = 5 yrs
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